It's a designed feature -exist slot- specifically engineered to kick out >> any peddles/sticks/sand/debris that gets thrown into the chassis ,so to Not get caught/jammed into the center spur and pinon.
Leave it be..
It'll save you the headache of having damaged/missing teeth on those critical gears.
Do you guys who have the scorched fenders cover this up? I have run into grass or leaves before and gotten debris in the chassis From the hole and sprayed laterally by the gear. I intend to cover this hole if my damned scorched fenders ever get here.
I think my local delivery company was too damn lazy to deliver and my stuff is stuck in limbo right now